Canine evolution

The company of wolves

Man’s best friend originated in Europe, not East Asia

FOXES can be tamed deliberately, by selective breeding (see article). But this probably recapitulates a process that happened accidentally, many millennia ago, to wolves. The product of that was the animal now known as the dog. But where on Earth this happened is moot. Fossils have been used to make the claim for places as diverse as Russia and the Middle East. Genetic evidence has pointed towards East Asia, with some people believing that New Guinea singing dogs and their Australian offshoots, dingoes (see picture above), are largely unchanged descendants of the first pooches. Olaf Thalmann of the University of Turku, in Finland, Robert Wayne of the University of California, Los Angeles, and their colleagues beg to differ. They think Fido was born in Europe, and that they have the DNA to prove it.

The DNA in question is from mitochondria: cellular power packs that have their own genes. Because each cell has lots of mitochondria, but only one nucleus, there is a better chance of getting mitochondrial genes than nuclear genes from a fossil. And that, as they describe in Science, is what Dr Thalmann, Dr Wayne and the rest of the team did.

They extracted mitochondrial DNA from 18 fossil canids, making sure to include the earliest doglike creatures that show skeletal signs of domestication. (These date from 36,000-15,000 years ago.) They then compared what they found with DNA from 49 modern wolves collected from all over the northern hemisphere, and also with that from 77 modern dogs.

Modern dogs, they knew from previous studies and confirmed with this one, belong to four genetic groups—different branches of the canine family tree, in other words. Several fossil canids from Europe, the researchers found, also belong to one or other of these groups, as do the continent’s modern wolves. Middle Eastern and Asian wolves, both ancient and modern, are, by contrast, not members of any of these groups and cannot therefore be closely related to modern dogs.

Three dog fossils from the Americas, dating back between 1,000 and 8,500 years, also shared their ancestry with modern mutts. Presumably their forebears accompanied the first American colonists 15,000 years ago when they crossed the Bering land bridge that linked the New and Old Worlds before the sea level rose to flood it at the end of the last ice age.

Dogs’ division into four groups means one of two things. Either domestication happened more than once, or each group is descended from post-domestication crosses between dogs and wolves that brought new mitochondrial DNA into the line. Regardless of which is true, this study seems both to pinpoint where dogs come from and to confirm that their domestication predates the invention of agriculture, about 10,000 years ago.

For reasons yet unknown, wolves and humans first got together when people still hunted and gathered for a living. Perhaps their similar ways of life—both species then dwelling in small, mobile bands—allowed the two to collaborate in hunting or defence. Or perhaps they just enjoyed each other’s company. Rather like today, in other words.